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The article [1] describes specific features of positron trapping in silicon plastically deformed at room temperature. The results are related to the dislocation core structure and the inhomogeneous deformation. The picture shows the probability density function of a positron localized in a vacancy in silicon. The calculation was performed with the superimposed-atom model. The degree of localization and consequently the defect-related positron lifetime vary for different open-volume defects, such as vacancies, voids, and dislocations. The first author, Hartmut S. Leipner, is CEO of the Center of Materials Science of the University Halle–Wittenberg. His research activities are focused on the characterization of extended defects in semiconductors.

Micro-indentation tests performed from room temperature to 700 °C on LaAlO 3 single crystals show a plastic anisotropy in the rhombohedral phase, depending on the orientation of the Vickers indenter. The indentation-induced twins were investigated by atomic force microscopy. Their geometry appears to be different from those resulting usually from the cubic to rhombohedral phase transition.

Dislocations in (Hg, Re)Ba2Ca2Cu3O8+ δ superconducting ceramics plastically deformed at room temperature have been characterized by transmission electron microscopy (TEM). Samples were submitted to strain levels up to 8, 18 and 63% by uniaxial compression under a confining pressure. Dislocation densities within grains were found to be in the range 109–1012 cm−2. The average grain size decreases from about 20 μm in the as-grown material to about 0.5 μm for the sample deformed up to 63%. Evidence for (001)⟨ 100⟩, (001)⟨ 110⟩ and glide systems was obtained by TEM. Dislocations are characterized by long straight screw segments and shorter edge parts. These features are interpreted as resulting from high Peierls valleys along the ⟨ 100⟩ and ⟨ 110⟩ screw directions. Cross-slip as well as climb dissociation of ⟨ 110⟩ dislocations occur. The shape of deformation-induced dislocations, their evolution during deformation and the interaction between dislocations in the (001) ⟨ 110⟩ and { }⟨ 110⟩ glide systems are dis...

AlPdMn quasi-crystalline specimens were deformed at low temperatures using a high-confining-pressure device. The microstructures, observed in each sample by transmission electron microscopy, depend on the deformation temperature and show that plastic deformation is accompanied by dislocation movements. A detailed analysis of the dislocation configurations shed light on the low temperature deformation mechanisms. (C) 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

To evaluate phytoremediation potentialities by metal accumulation in tolerant plants, trials are carried out using in vitro cultures. Organic compounds influence on metal accumulation is studied with metals supplemented media. The tested compounds on zinc and lead absorption by Brassica juncea, are chelating agents (EDTA, citric acid) and soluble organic fractions of compost. EDTA seems to enhance the transfer of lead in plant but it is the opposite in the case of zinc. Citric acid stimulates root absorption for both zinc and lead. For the aqueous extracts of compost, variable effects are obtained according to the origin of compost (green wastes and food wastes). In all tested conditions of cultures, zinc is mainly exported towards shoot while lead is stored in root.

Plastic deformation of Al-Pd-Mn icosahedral quasicrystals has been achieved at room temperature using a high-confining-pressure medium. The deformation microstructure, investigated by transmission electron microscopy, is characterized by long straight bands of dislocations. A detailed analysis of the dislocation configurations indicates that the plastic deformation is controlled by dislocation glide.

We have examined the various possible configurations for an undissociated screw dislocation in group IV materials (Ge, Si, 3C-SiC, diamond) by means of semi-empirical atomistic calculations. A complete structural characterization and a determination of the relative stability are performed. We found that, in contrast to the case for Ge and Si, a geometry with the presence of sp 2 atoms in th ec ore is the most stable structure for 3C-SiC and diamond. This yields a stable screw dislocation configuration i nt he ‘shuffle’ set for Si and Ge, and in th e‘ glide’ set for 3C-SiC and diamond.

The microstructure of 4H–SiC single crystals deformed under very high stresses and at low temperature (T ≤ 350°C) have been analysed by transmission electron microscopy. Depending on deformation conditions, large stacking faults, weakly dissociated perfect dislocations and possibly undissociated perfect dislocations have been observed. From these results, it appears that the nucleation of partial dislocations, which is a limiting process in deformation of 4H–SiC below ~1000°C, can be helped by very high stress. Consequently, it is not excluded that a deformation mechanism by undissociated perfect dislocations can take place under very high stress, as observed in Si and GaAs.

The microstructure of subboundaries (SBs) occurring in single domain YBa2Cu3O7 (Y123) melt textured composites is studied by transmission electron microscopy. The form of SB dislocation networks is controlled by the properties of constituting dislocations. For arbitrary SB configurations, it can be parametrised using the generalised Frank's formula, allowing the calculation of dislocation densities, and an estimation of the SB critical current. Besides the underlying dislocation networks, SBs may develop mesostructures like faceting and stepped interfaces accommodating the deviation from low index planes. Implications of the observed microstructures on the bulk critical currents are addressed.

The dislocation substructure of melt-textured YBa2Cu3O7-Y2BaCuO5 composites deformed under uniaxial compressive stress and a superposed gaseous confining pressure has been investigated by transmission electron microscopy. Observations reveal the generation of perfect dislocations in (001) as well as out of this plane. Screw segments of the latter lying on (001) are seen to act as Frank-Read sources for ⅙ 〈301〉 partials bounding YBa2Cu4O8-type stacking faults, according to a mechanism previously anticipated from theoretical considerations by one of the present authors.

The evolution of the microstructure of melt-textured YBa2Cu3O7−Y2BaCuO5 (123–211) composites in O2 at 100 bar and 600°C has been characterized by transmission electron microscopy (TEM). Under these conditions the 123 phase is brought out of its stability field, within a region of the phase diagram where the weakly superconducting YBa2Cu4O8 (124) polytype is stable against a CuO + 123 mixture. The nucleation of 1/6 (301) stacking faults is not restricted to the 211–123 interfaces, as found in samples processed at 350 and 450°C but is strongly enhanced in the bulk matrix. Simultaneously, matrix decomposition into a Ba-Cu oxide, 211 and presumably CuO occurs at 211 interfaces, which is accompanied by an exaggerated growth of the stacking faults. After 12 h at PO2 = 100 bar and 600°C, the whole volume imaged by TEM appears to be covered by large stacking faults overlapping along the c axis. It is found that, when the 211 interfaces become saturated by stacking faults, new stacking faults have to nucl...

Several thermomechanical treatments have been used in order to create specific microstructures of dislocations in melt textured grown (MTG) YBa 2 Cu 3 O 7 m i /Y 2 BaCuO 5 ceramic superconductors. To by-pass the extreme brittleness of those materials, suitable techniques have to be used in order to increase substantially the dislocation density, in the orthorhombic phase, without promoting crack nucleation. The main features of microstructures obtained using e cold isostatic pressing f , high oxygen pressure anneals and plastic deformation under confining pressure are presented. The effects of applied stresses and phase instability on dislocation configurations are discussed together with the dislocation interactions with mirror twin boundaries. Consequences of those microstructures on the physical properties are also addressed with reference to the signature of each type of the defects.

International audience; Elements uptake, histological distributions as well as mycorrhizal and physiological statuses of Atriplex halimus were determined on trace metal and metalloid polluted soils from the surrounding spray zones of a former lead smelter in the South-East coast of Marseille (France). Analyses of heavy metal and arsenic distribution in soil and plant organs showed that A. halimus tolerance is largely due to exclusion mechanisms. No specific heavy metal concentration in leaf or root tissues was observed. However, accumulation of salts (NaCl, KCl, Mg and Ca salts) on leaf bladders and peripheral tissues of roots was observed and may compete with metal element absorption. Occurrence of endomycorrhizal structures was detected in roots and may contribute to lower element transfer from root into the aerial parts of plants. The non-destructive measurements of leaf epidermal chlorophylls, flavonols and phenols showed a healthy state of the A. halimus population on the metal and metalloid polluted sites. Considering the low metal bioaccumulation and translocation factors along with a reduced metal stress diagnosis, A. halimus appeared as a good candidate for phytostabilization of trace metals and metalloids and notably arsenic in contaminated soils of the Mediterranean spray zone. However, its invasive potential has to be determined before an intensive in situ use.

This paper concentrates on dislocation plasticity and microstructural features in ceramic materials. The consequences of some features of the dislocations are examplified and compared with those of metallic and semi conducting materials.

Dislocation configurations resulting from high stress low temperature deformation in silicon are found non-dissociated and elongated along different Peierls valleys as compared to usual results from the literature. Experiments on pre-deformed samples are reported and discussed in the context of a possible transition in the core structure at high stresses between dissociated glide and perfect shuffle configurations.

Dislocation microstructures induced by room-temperature microhardness tests have been investigated in silicon nitride. Surface analysis of the residual indent by atomic force microscopy reveals intragranular slip bands and demonstrates that room-temperature plastic deformation involves dislocation motion as well as cross-slip events. Cross-slip events have been found to occur between {1010} prismatic planes. Transmission electron microscopy shows that dislocations have a Burgers vector b = [0001] and are located along the screw direction. Based on these observations, specific dislocation core configurations are discussed.

Macroscopic plastic deformation of silicon single crystals has been achieved at RT and 150°C under a confining pressure of 5 GPa in a multi-anvil apparatus. TEM observations of a sample deformed at 150°C show that the deformation microstructure is built with dislocations with 1 2 a 1 1 0 Burgers vector in (1 1 1) planes which are undissociated. They appear as mainly aligned along the screw orientation and 〈1 1 2〉 orientations at 30° from the Burgers vector. Those features are analysed in the light of perfect dislocation generation in the shuffle set.

Microstructures associated with room temperature indentation subsequently annealed at 450°C have been analyzed by TEM in Y and Nd based melt textured ceramic superconductors. It is shown that stress relaxation around indentations occurs by the nucleation of stacking faults with R = 1/6〈031〉 displacement vector in Y based material. Differently relaxation occurs in NdBaCuO by the nucleation of perfect dislocations with 〈100〉 Burgers vectors which can be locally dissociated. A model is proposed to explain these microstructures and is related to the difference in energies of stacking faults with R = 1/6〈031〉 displacement vector in these compounds.

Dislocation microstructures induced by plastic deformation at room temperature in Si have been investigated by TEM. Plastic deformation has been obtained by using two types of technique: deformation under a confining pressure of 5 GPa in an anisotropic multi-anvil apparatus and by surface scratching. The TEM observations show common features in the two deformation substructures which are characteristic of high stress-low temperature deformation. The deformation microstructures are built with dislocations with a/2110 Burgers vector in (111) planes which are undissociated. Such dislocations are mainly aligned along the screw orientation and 112 orientations at 30° from the Burgers vectors as well as along 132 orientations at 41° from the Burgers vector. The occurrence of those Peierls valleys confirms that different dislocation core configurations from those usually dealt with at higher temperatures have to be taken into account when dislocations are nucleated at very high stresses.

Intragranular plasticity induced by indentation is studied in β Silicon Nitride between room temperature and 700°C by Transmission Electron Microscopy (TEM). It is shown that all the dislocations resulting unambiguously from plastic deformation have a Burgers vector b = [0001] and a dominant screw character. This can account for a large Peierls stress along the [0001] direction and a larger mobility of edge dislocation segments as compared to screw ones. Dislocations bowing out of screw direction are found to glide in [1010] prismatic planes. Cross-slip is evidenced from the dislocation microstructure observations. It is found to occur between {1010} prismatic planes at 20°C whereas {1120} is found to be a new deviation plane at 700°C. Those observations are discussed in relation with the possible core structure of [0001] screw dislocations.

The deformation microstructures of Si single crystals have been studied by transmission electron microscopy (TEM) in the temperature range of deformation where “dislocation trails” are evidenced. The main features of the deformation microstructures are characterized by dislocations dipoles and their debris. These microscopic observations are discussed in relation with the mesoscopic properties of dislocation trails as well as the possible transformation between two different core structures of dislocations in silicon.

This proceedings issue of physica status solidi contains papers presented as oral and poster contributions at the International Conference on Extended Defects in Semiconductors (EDS 2008). This conference was held in France at the new campus of Poitiers University situated in the Futuroscope area on 14–19 September 2008 and was organized by PHYMAT laboratory (UMR 6630 of CNRS and University of Poitiers). The EDS conference series was inaugurated in Hunfeld (Germany) and was followed by conferences in Poland, France, Great Britain, Germany, and Russia. The EDS 2008 is the direct follower of the conferences of 2004 held in Chernogolovka (Russia) and 2006 in Halle (Germany). The aim of the conference was to provide a forum on the current state-of-the-art of investigation and modelling of extended defects in semiconductors in order to achieve a deeper understanding of lattice imperfections, their interaction, and their role in the development of semiconductor technology. The following main topics were covered: – Relation between extended defects and nanostructures in semiconductors – Defect structure: defect imaging and modelling – Electronic structure of extended defects – Mechanical properties and dislocations: nucleation and dynamics – Interaction between defects – Structure of strained layers – Defects in thin films and interfaces, interface structures – Role of extended defects in devices, defects engineering – Narrow and wide band gap materials – Defects in solar cell materials and photovoltaic devices – Embedded semiconductor nanoparticles, quantum dot like “extended defects” – Implantation-induced extended defects As a new approach, we emphasized semiconductor behaviour under severe environment (high temperature, complex and high stress field and irradiation). Indeed, both experimental and modelling approaches of extended defect nucleation and properties deserve challenging understanding under these harsh conditions, in which important applications are expected for semiconductors. We wish to thank the members of the EDS 2008 Scientific and Organizing Committees, the sponsors, as well as the referees and authors who made this conference and proceedings a success. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Reference CRPP-ARTICLE-1999-033doi:10.1016/S1359-6462(99)00242-0View record in Web of Science Record created on 2008-04-16, modified on 2017-05-12

Single domain YBa/sub 2/Cu/sub 3/O/sub 7/-Y/sub 2/BaCuO/sub 5/ melt textured ceramic composites have revealed a very rich microstructure, which has usually impeded, by using standard measurements, to evaluate the contribution of each defect to the enhancement of the critical current. We have measured the in-plane magnetoresistance anisotropy and the anisotropic in-plane inductive critical currents and we show that together with the microstructural TEM analysis, the contribution of the different extended pinning centers can be separated. These results have allowed us to infer the kind of microstructure modifications required to improve the critical current. In particular, we present an isostatic pressing deformation technique as a very promising post-processing treatment to strongly increase the critical currents of these composites

The problem of transient primary or secondary metabolism remaining a persisting problem in plant cell cultures is discussed. Since secondary metabolites occurred mainly in differentiated tissues, an effort was made to mimic the cell-to-cell contact of multicellular organisms. Sucrose metabolism and indoleglucosinolate production from immobilized cells of Armoracia rusticanawere investigated. Immobilization acted by reducing the assimilation of the hexoses released into the culture medium. Although sucrose hydrolysis occurred prior to uptake, the decrease of acid invertase activity in immobilized cells was accompanied by an increased yield (2–3-fold) of the intracellular sucrose. Glucosinolates accumulated as indolic forms only during the stationary stage of cell growth. Their amount in immobilized cells may be increased 2-fold compared to the control cultures. On the other hand intracellular sucrose concentration declined whilst the cleavage activity of sucrose synthase increased simultaneously with production of indole-3-methyl- and 4-hydroxy-indole-3-methyl-glucosinolates. Thus, the role of cell immobilization in the biosynthesis of indoleglucosinolates is discussed.

Partial dislocation nucleation and multiplication in III–V semiconductor compounds are usually ascribed to the difference in mobility between α and β partials. These differences in mobility increase when the temperature decreases, so that the contribution of twinning to the deformation mechanisms becomes important for high stresses and low temperatures. Starting from transmission electron microscopic observations of plastically deformed InSb under high stresses and hydrostatic pressure at room temperature, showing the multiplication of α as well as β partial dislocations, a model for the partial dislocation multiplication is proposed. This model does not rely on the difference in α and β partial dislocation mobilities but on the formation of Lomer-Cottrell sessile dislocations issued from dislocation dipoles. Les phenomenes de nucleation et de multiplication de dislocations partielles dans les semi-conducteurs III–V sont habituellement attribues a la difference de mobilite entre les partielles α et β. Cette difference de mobilite augmente lorsque la temperature diminue, de sorte que la contribution du maclage dans les mecanismes de deformation devient importante pour les fortes contraintes et les basses temperatures. A partir d'observations en microscopie electronique en transmission de InSb deforme a temperature ambiante sous fortes contraintes et sous pression hydrostatique, mettant en evidence la multiplication de dislocations partielles α et β, nous proposons un modele de multiplication des dislocations partielles. Ce modele ne fait pas appel a la difference de mobilite entre les dislocations partielles α et β, mais il fait intervenir la formation de dislocations sessiles de Lomer-Cottrell a partir de dipoles de dislocations.

From observations of extended dislocation nodes in β silicon nitride, possible stacking fault structures in the basal plane of this compound have been investigated. It has been found that stacking fault structure is locally analogous to α silicon nitride. A phase transformation α to β or β to α can also be achieved by cooperative shear of partial dislocations with Burgers vectors.

The influence of dislocations on pinning of vortices has been investigated in melt-textured YBa 2 Cu 3 O 7− x and YBa 2 Cu 3 O 7− x ceramics. The dislocations, introduced by plastic deformation at room temperature in the orthorhombic phase, are characterized using transmission electron microscopy. dc and ac magnetic measurements revealed that the plastic deformation of melt-textured samples induced a decrease of the activation energy for flux motion. This effect has been related in a preceding paper to the microcracks created in important density along the (001) planes during the deformation process. The comparison of these results with those obtained on a ceramic material confirms this interpretation.

This paper considers the plasticity of InSn under high stress, at low temperatures. The studies cover the plasticity of InSh in the temperature range between 20 and 200°C and under stress which is applied by superimposing uniaxial pressure on a confining hydrostatic pressure. The analysis of the deformed substructures by transmission electron microscopy revealed the existence of different deformation mechanisms at different temperatures, and consequently. stress regimes At temperatures T ≥ 50°C the dominant deformation mechanism is the glide of perfect dislocations, while at room temperature the deformation can be attributed to partial dislocations. At lower temperatures. screw dislocalions become dominant, a fact that demonstrates the small mobility of these dislocations. Extended stacking faults introduced by the dissociation of β-type segments demonstrate the higher mobility of the 90 β partial dislocations conspired to the mobility of the 30 β ones. In contrast, the absence or extended dissociation for the 60 α-type dislocations suggests that the 90 α and the 30 α partial dislocations have the sortie mobility An additional interesting issue arises from the observations showing a small difference in mobility between the 30 α and the 30 β partial dislocations The significance of these observations is discussed and the results are correlated to similar observations in other III-V compounds.

Dislocations substructures in aluminium nitride (AIN) ceramics have been studied by transmission electron microscopy for samples plastically deformed under a high stress in the temperature range 20–800°C. The activation of basal slip ⅓ 〈1120〉(0001) as well as of the first-kind prismatic slip ⅓ 〈1120〉{1100} have been observed. In the basal plane, dislocations configurations attest to the role of the Peierls forces along the screw orientation. It is easier for a dislocation to cross-slip in the prismatic plane than to lie in the basal plane along an orientation other than the screw direction. In the basal plane as well as in the prismatic plane, no dissociation of dislocations has been resolved under weak-beam imaging conditions. Cross-slip is favoured by numerous pinning points on screw dislocations, giving rise to dipole dragging. From 20 to 500°C, AIN deformation proceeds by dislocation glide in the basal and the prismatic planes and frequent corss-slip between these two planes. At higher temper...

Observations of dislocation substructures have shown that the basal and first-kind prismatic planes are easily activated in plastically deformed aluminium nitride between room temperature and 800°C as shown in the companion paper, part I. In this paper, several analyses are performed to determine the ability of dislocations to glide in one plane relative to others. According to the closest-packed criterion, the first-kind prismatic plane appears to be favoured. Line energy calculations under anisotropic elasticity do not allow one to conclude the preferential activation of one of the glide planes. The crystallographic structures of basal and first-kind prismatic planes, core structures of dislocations and dissociation reactions are investigated and stacking-fault configurations in prismatic planes are proposed.

The microstructure of YBa2Cu3O7−x −Y2BaCuO5 melt-textured composities deformed in the secondary and tertiary creep regimes has been investigated by transmission electron microscopy. The high density of Y2BaCuO5 precipitates plays an important role in the microstructural development as pinning sites for gliding dislocations. In the secondary regime, trapped dislocations are dissociated, leaving a stacking fault with displacement vector [½—δ 0 ⅓]. A second stacking fault, ⅙〈301〉, is typically associated with the former stacking fault. At this stage, the deformation microstructure is dominated by diffusive processes between precipitates interconnected by the trapped dislocations. In the tertiary stage, dislocation multiplication is the main factor controlling the microstructure, which is characterized by a dramatic increase in the density of perfect dislocations with Burgers vectors 〈100〉 and 〈110〉. Since deformation is performed above the orthohombic-to-tetragonal transition temperature, the sample...

The microstructure and superconducting properties of directionally solidified YBa2Cu3O7/Y2BaCuO5 composites made to creep at 930°C, have been investigated using transmission electron microscopy, and dc and ac magnetic measurements. It is found that the plastic deformation of high critical current samples induces a shift of the irreversibility line toward lower fields and temperatures as a result of a decrease of the activation energy for flux motion. Such a superconducting behaviour is directly correlated with the observed microstructure, which is dominated by microcracks and large stacking faults that decrease the vortex correlation along the c axis.

The intercalation of CuO layers in the 123 compound is analysed in terms of the movement of partial dislocations in the matrix, assisted by CuO diffusion. The influence of an external stress on the nucleation of such a CuO layer in a perfect or in a dislocated crystal is discussed. A model of a partial dislocation Frank-Read source, diffusion assisted, is proposed for the formation of polytypoids.

Some preliminary results of dislocation analysis and associated glide systems in as-grown as well as in superplastically deformed β silicon nitride are presented. Transmission electron microscopy observations using the weak-beam technique, are reported. [0 0 0 1] {1 0 1 0} and 1/3〈1 2 1 0〉 {1 0 1 1} glide systems have been characterized. In the basal plane, a superposition of two hexagonal networks built with screw dipoles has been observed. Both a sequence extended node–constricted node and partial dislocations have been identified in these networks which clearly evinces dislocation dissociation in β-silicon nitride following the reaction 1/3〈2 1 1 0〉→1/3 〈1 0 1 0〉+1/3 〈1 1 0 0〉.

International audience; Plastic deformation of a 4H-SiC wafer has been produced by nanoindentation at room temperature. The superficial layer of the specimen in the indented area has been lifted out thanks to a specific focussed ion beam micromachining method and the deformation microstructure close to the imprints has been investigated by means of both conventional and high-resolution transmission electron microscopy (TEM). The analysis of the images revealed the presence of various types of extended defects. Perfect dislocations and single stacking faults bounded by isolated Shockley partial dislocations have been observed on the basal plane. Perfect dislocations have also been evidenced out of the basal plane. These results highlight the competition between various activated systems involved during the plastic deformation of 4H-SiC in the brittle regime.

International audience; This study aimed at estimating exposition risks to wild rosemary used as herbs in the contaminated area of the former smelting factory of L'Escalette (South of Marseille, France). Metals and metalloids i.e. Pb, As, Sb, Zn, and Cu concentrations were analyzed in soils and in rosemary aerial parts (stems and leaves) on two sites: one heavily contaminated and the other far away from the pollution source, considered as reference, The metal and metalloid transfer into water during the brewing process of herbal tea was also determined. A mixed contamination by the above-cited contaminants was demonstrated in soils of the factory site, with average concentrations of 9253, 1127, 309, 2698 and 32 mg/kg for Pb, As, Sb, Zn and Cu, respectively. However, metals and metalloids' transfer in rosemary aerial parts was limited, as bioaccumulation factors were under 1. Thus, Pb, As and Cu concentrations in leaves were below international regulation limits concerning ingestion of medicinal herbs (no regulation values available for Sb and Zn). This study highlighted that, if contaminated rosemary leaves were ingested, health risks may be limited since acceptable daily intake (ADI) for Pb, As, Sb and Cu (no ADI value available for Zn) will only be reached if very high quantities are consumed. Furthermore, we aimed to establish if this mixed contamination could alter rosemary's essential oil quality, and thereby the compositions of essential oils obtained from individuals on the heavily contaminated soil were compared to those obtained from the reference population. An increased biosynthesis of antioxidant compounds was favored in essential oils from rosemary individuals growing in contaminated site. Although the health risk of a long-term exposition of low level of the mixed contamination by rosemary ingestion is not easy to elucidate, the use of rosemary essential oils from contaminated site appears as safe. (C) 2013 Elsevier B.V. All rights reserved.

International audience; This study aimed at identifying the extent and type of contamination of a former lead smelting site in the area of Marseille, France, dating from the industrial revolution, and to evaluate environmental hazards and opportunities for phytoremediation, a promising sustainable technology. Amongst the native plants growing in this semiarid shrub ecosystem, two perennials Globularia alypum L. and Rosmarinus officinalis L were selected. Twenty-one soil/plant couples were collected and seventeen additional soil samples were added to better characterize the soil pollution of the area. A multi-contamination by Pb, As, Sb, Zn, Cu was demonstrated, with huge variations within the contamination levels. The soils highest concentrations were encountered along the horizontal chimney and on the slag heaps area. However, both sites differed from each other. The former was characterized by the highest Pb, As and Sb concentrations that could reach 130, 7.0 and 9.0 g kg(-1) respectively, the latter, by high Cu, Fe, Mn, S concentrations, even if it was also heavily contaminated by Pb and Zn. G. alypum and R. officinalis were shown to be metal-tolerant and to accumulate trace metals and As. Due to the low bioconcentration and translocation factors determined, both species may not be used for phytoextraction, but seem to be good candidates for phytostabilization. (C) 2013 Elsevier B.V. All rights reserved.

Discrepancies exist in the literature about the formation and atomic structure of intercalated CuO layers in YBa2Cu3O7−δ, the so-called ⅙[031] stacking faults. In this paper the fault structures are re-analysed depending OR whether the additional CuO layer has expanded into a tetragonal matrix or an orthorhombic matrix. Of particular interest are the interaction features of such a fault with mirror twin boundaries.

International audience; This study was aimed at assessing the impact of urban agriculture on physicochemical properties of the soil and the metal uptake by some leafy vegetables cultivated in urban soils of Libreville, Gabon. Cultivated and uncultivated topsoil and vegetable samples were collected from two urban garden sites, and analyzed. The results showed that there was strong acidification and a decrease in the concentrations of nutrients and metals in soils due of agricultural practices. The metal transfer to plants was important, with the exception of iron. The non-essential metals cadmium and lead were not detectable in the plant tissues. Amaranth accumulated more metals than other vegetables. Amaranth and Roselle were vegetables that preferentially concentrated metals in their leaves and could, therefore, be used for metal supplementation in the food chain.

This paper deals with the properties of dislocations in some ceramic materials. The implication of the intimate structure of dislocations revealed at the TEM level, on the macroscopic properties is discussed. Not only consequences on mechanical properties are taken into account but also consequences on physical properties. Examples are given for structural ceramics (ZrO2), as well as for superconducting ceramics (YBa2Cu3O7-∞). In this latter class of materials it is shown that dislocations can be used to locally change the thermodynamic range of nucleation of non stoichiometric phases. Pinning of vortices by dislocations is also discussed.

International audience; The 3C-6H polytypic transition in 3C-SiC single crystals is studied by means of diffuse X-ray scattering (DXS) coupled with transmission electron microscopy (TEM). TEM reveals that the partially transformed SiC crystals contain regions of significantly transformed SiC (characterized by a high density of stacking faults) co-existing with regions of pure 3C-SiC. The simulation of the diffuse intensity allows to determine both the volume fraction of transformed material and the transformation level within these regions. It is further shown that the evolution with time and temperature of the transition implies the multiplication and glide of partial dislocations, the kinetics of which are quantified by means of DXS.

The larvicidal activity of ethanolic leaf extracts from two Artemisia species, Artemisia campestris var. glutinosa and A. molinieri, on mosquito Culex pipiens Linnaeus (Diptera, Culicidae) larvae was investigated. Since A. molinieri is a rare and protected species confined to temporary ponds of Southern France, its toxic activity may help to value this species and to finance its conservation. A. molinieri extracts showed a higher larvicidal activity (from 50 ppm (K = 9.488, DDL = 4, P < 0.001)) than those from A. campestris var glutinosa (from 500 ppm (K = 9.488, DDL = 4, P < 0.01)) after 48 h of exposure. Calculated lethal concentrations, after 48 h of exposure, (LC50) were low, 9091 and 9898 ppm for A. molinieri and A. campestris var. glutinosa extracts, respectively, but using a non-pollutant solvent (ethanol). However, A. molinieri may be valued as an environmentally friendly biocide and developing its culture may be of interest for both pesticide activity and conservation purpose.

A Comment on the Letter by V. L. R. Jacques et al., Phys. Rev. Lett. 106, 065502 (2011). The authors of the Letter offer a Reply.

In this work, the kinetics of the 3C-6H polytypic transition in 3C-SiC single crystals are studied in details by means of diffuse x-ray scattering (DXS) coupled with numerical simulations and transmission electron microscopy and optical birefringence microscopy. Upon high-temperature annealing, spatially correlated stacking faults (SFs), lying in the {111} planes, are generated within the crystal and tend to form bands of partially transformed SiC. It is shown that the numerical simulation of the DXS curves allows to unambiguously deduce the transformation level within these bands, as well as the volume fraction corresponding to these bands. Increasing annealing time results (1) in the growth of the partially transformed regions by the glide of the partial dislocations bounding the SFs and (2) in the generation of new SFs within the crystal by means of a double-cross slip motion. The kinetics of each of these mechanisms are presented and discussed with respect to the annealing temperature, the initial SF density and crystalline quality.

In a context of ecological restoration, the use of local source plant populations may be successful for both reclaim of areas polluted with inorganic compounds and biological conservation. Knowing that contaminated sites are generally poor in nutrients and contain a highly altered soil structure, mycorrhizal fungi and rhizobial nodulation are suspected to play an important role in vegetation establishment. The aim of our study was to evaluate the potentiality of an endemic plant species of South-Eastern France, Astragalus tragacantha L. (Fabaceae), to re-colonize an abandoned industrial polluted site. We first grew seedlings of three local populations on soil polluted by heavy metals from the surrounding factory and various growth parameters were measured, after one and two years. Second, arbuscular endomycorrhizal colonization and rhizobial nodulation were determined. Our results are promising because i) A. tragacantha appeared to be heavy metal-tolerant and ii) this is the first report on the occurrence of both endosymbioses for this plant species. This opens new perspectives for dual inoculation with selected rhizobium and arbuscular mycorrhizal strains, in a context of community ecological restoration with this key-species of phryganas from South-Eastern France. This study helps improving the connection between biodiversity conservation and restoration ecology and founding strategies for the propagation of native seeds for ecological restoration resulting in long term population viability., L’utilisation de populations locales comme source de plantes dans le cadre de processus de restauration écologique permet de parvenir à la fois à la réhabilitation de sites pollués par des composés inorganiques et à la conservation biologique. Les sols contaminés étant généralement pauvres en nutriments et présentant une structure hautement altérée, il est supposé que les associations mycorhiziennes et rhizobiennes jouent un rôle non négligeable dans la colonisation végétale. Ainsi, l’objectif de ce travail a été d’évaluer la capacité d’une espèce endémique du sud-est de la France, Astragalus tragacantha L. (Fabaceae) à recoloniser un ancien site industriel pollué. Des plantules issues de graines provenant de trois populations locales ont été transplantées dans du sol pollué prélevé aux alentours du site industriel. Des mesures de croissance ont été réalisées après une et deux années de culture. D’autre part, l’importance des colonisations endomycorhiziennes et rhizobiennes a été évaluée. Nos résultats sont prometteurs parce que 1) A. tragacantha apparaît comme tolérante aux métaux lourds et 2) c’est la première mise en évidence de la présence d’une double endosymbiose chez cette espèce. En effet, cela permet d’envisager une double inoculation de souches rhizobiennes et endomycorhiziennes sélectionnées pour favoriser la restauration écologique des phryganes du sud-est de la France en utilisant cette espèce clé sur des zones polluées par des éléments traces métalliques. Cette étude contribue également à montrer le lien étroit entre conservation de la biodiversité et restauration écologique en étudiant des stratégies de propagation des espèces natives dans un objectif de viabilité des populations à long terme., Laffont-Schwob Isabelle, Dumas Pierre-Jean, Pricop Anca, Rabier Jacques, Miché Lucie, Affre Laurence, Masotti Véronique, Prudent Pascal, Tatoni Thierry. Insights on metal-tolerance and symbionts of the rare species Astragalus tragacantha aiming at phytostabilization of polluted soils and plant conservation. In: Ecologia mediterranea, tome 37 n°2, 2011. Numéro spécial, 7e conférence européenne SER en écologie de la restauration, 23-27 août 2010, Avignon, France. pp. 57-62.